Differences in Plantar Foot Pressure and COP between Flat and Normal Feet During Walking

[Purpose] The purpose of this study was to compare the peak plantar foot pressure and the pathway of the center of pressure (COP) between normal and flat feet. [Subjects and Methods] Nineteen subjects (10 normal feet, 9 flat feet) participated in this study. Plantar foot pressure was recorded by the Matscan system (Tekscan, Boston, USA) while walking upright. Plantar foot surface was divided into seven regions for pressure measurement: two toe regions, three forefoot regions, one midfoot region, and one heel region. The independent t-test was used to compare plantar foot pressures between normal adults and patients with flat feet. The pathway of COP in normal and flat feet was observed macroscopically. [Results] The plantar foot pressures of the 4th-5th metatarsal head and heel regions in the flat feet group were less than those of the normal feet group. The pathway of COP of normal feet group had a tendency to shift medially in the forefoot but the pathway of COP in the flat feet group had a tendency to be straight in the forefoot. [Conclusion] The results indicate that the plantar foot pressure of a flat foot was lower than that of a normal foot and the pathway of COP of a flat foot may be different from that of a normal foot. We believe that reduction of the longitudinal arch of foot in flat feet explains these results.